After several plant casualties, my windowfarm is recovering from its pH fever. The lettuce survived and started to grow again, as the nasturtium, three basils and most of the peas (these lasts started to flower, as a matter of fact. Beside a thorough clean-up, the only thing I did for those survivors was to entirely change the composition of their nutrient solution.

So, right now, my upper reservoirs contain water from the tap (pH 7, has been sitting at least 24 hours to let chlorine evaporate before use) and an organic nutrient bought at the Hydroponic store : Iguana Juice Grow (it automatically gets the water pH down to 5,5 but smells like dead fish – really awful since it gets the room smelly at times). Take note that my system is working on gravitation, so I have to refill the reservoirs by hand, something I need to do about every four to eight days, usually, depending on the dripping flow. Therefore, the water doesn’t recirculates in the system unless I decide to reuse the contents of the bottom reservoir.

So, I started anew in one column, cleaning up everything, boiling the clay pellets, discarding the old rock wool and using fresh nutrient solution with Iguana Juice and my worm compost tea. Then I monitered the pH very closely.

Here is what I discovered :

1. My precious worm compost tea has a pH over 8,5 ! I never thought of testing it before my plants started to suffer very seriously. I always tested my pH after mixing in the nutrients and a few milliliters of vinegar to start with. Take note that within one column of my surviving plants, the pH would rise from 5,5 at the source up to 8,5+ in the bottom reservoir.

In the new column, the same phenomenom was observed, but to a much smaller extent (pH at 7 in the end). So, I stopped everything again and dumped the water solution to get rid of the worm tea.

Hypothesis : I use, from time to time, egg shells to protect my worm compost from too much acidity. Obviously, I overdid it. And I think that microscopic eggshell particles lodged themselves within the rock wool, very slowly dissolving into the dripping water flow, thus affecting its pH.

2. Even after my stopping from using worm compost tea, the pH in the reservoirs still has a tendency to slowly (within 4 days) go back up from 5,5 to 7 right inside the upper reservoirs (therefore, it does that without getting in contact with the plants or the wool rock, or eggshell particles).

Hypothesis : there could be in the city water a kind of pH stabilization agent that would slowly raise it back up. But I think that I can manage this imbalance by readjusting the pH every other day.

In the meanwhile, I isolated 50 of my worms in a new container to start a new compost farm. I will monitor its pH very closely to try to produce a worm tea with a pH of 6 or 6,5 at the most without any eggshells in it.

I intend to leave the two old columns as they are (with the old rock wool and the surviving plants), to see if the pH alteration effect wears off. The two other columns will receive new plants in new rock wool, and no worm tea will enter in my nutrient mixture until it has a more suitable pH reading !

All this thrilling mystery is fascinating and I have the feeling that I learn a little more everyday, although it was heartbreaking to see my plants die and quite panicking not to have a clue as why.

Your PH problem is very interesting. I would have thought that the calcium in the eggshells is good. (It would act as a buffer against low PH.)
Perhaps we need to look a bit more at buffers to keep PH in the best range.
What about ammonia as a cause?
Maybe something is breaking down nitrogen compounds and producing ammonia which is basic and would cause a rise in the PH?

Yes, I measured pH from a bucket of water : it remains stable à 7.
From the beginning, I always filtered my compost tea with a coffee filter. Sometimes the tea would come from the excess moisture sipping through the bottom holes of the container, other times, I would use the compost itself and make it steep in dechlorinated water before filtering it.
My reservoirs are well protected from light. Well enough not to produce algea, at hleast.
And yes, it seems that the eggshells do act as a buffer, raising the pH solution consistently over 8,5. I didn’t know the calcium could be the cause.
I extracted 50 of my worms and moved them to another container to start anew without any eggshells, so in a few months, I should be more sure about this egshell theory.
I’m not sure about ammonia, since I did try urea as a source of nitrogen only for a short period of time. Could it be stored in rock wool as I suspect eggshell particles could ? Do eggshell produce ammonia as well ?
Thank you very much helping me think my way through this fascinating enigma.

First of all, its not the calcium that is buffering the pH, its the carbonate. Calcium is quite inert in water (although its actualy a lewis-acid, but that will take us to far). Egg-shells are made of calcium-carbonate (CaCO3). I’d say leave the egg shells in. CaCO3 is very little soluble in water and will only be dissolved if the pH tends to go to low. So it’s good for your worms and not bad for the plants who can use the Calcium, especially if you would like to grow tomatoes and the like…

Secondly, since you use worm tea, I can imagine you have no idea what’s exactly in it. Since it’s home made it will most probably have loads of Dissolved Organic Carbon (DOC) in it. I suspect this is where the trouble starts… Since you are mimicking an organic layer of the soil within the worm container, it will also contain a lot of micro-organisms etc. When there is a lack of oxygen to oxidate (respirate) the organic carbon, the anaerobic types are kicking in. They use other compounds than oxygen as an oxidizing agent. One of the first to be used is nitrate (NO3-) which is reduced to ammonia (NH4+). This reaction can cause a very steep rise of the pH.

You have the same problem when you don’t use the worm tea. I’ve looked up the nutrient facts of the iguana juice. It’s says it has 3% water soluble nitrogen in it. Same problem as stated above. It will only take longer to rise the pH because there is so much DOC in the worm tea that the micro-organisms can grow very very rapidly!

What’s the solution? I would try to bring some more oxygen in the system. The substrate should not be completely damped all the time. Increase the dripping-trough speed a bit so that only about half an inch of your bottle is filled with liquid. Then capillarity of the rock wool will do the rest. If you see wilting problems, reduce the dripping a bit so more is left behind. Try shutting the dripping off during the night. Plants are consuming very little water when the sun is down. Be sure to be up early enough in the morning to put the water back on! You can always aerate the solution before you give it to the plants, but this will consume electricity to get the compressor working and I suspect you do not like that…

Hi, Agro-gio,
Hi !
Thanks a lot for your extended reply. I don’t know what motivated your taking of your personal time to answer my post, but it’s really appreciated.
It makes things a lot more clear. For instance, the fact that even after transfering my worms in a new litter and carefully avoid to give them eggshells, I still read a very high pH.
I’ll try first to areate my worm bin a lot more.
I’ve had a lot more success with the Iguana Juice, but it’s messy because it’s greasye and it tends to clog my float system. I had a good crop up to now.
Sometimes, the pH will raise after passing through the system, sometimes it will keep stable. So, I’ll pay attention to the oxygen factor.
Also, I noticed that plants don’t consume much water during night time and on cloudy days, so I cut the water for the night, and reduce the dripping flow when there’s no sun.
Using no electricity, the amount of oxygen diluted in the solution is an issue, and I suppose it gets worse with the passing days.
Maybe the reason I don’t notice it so much these days is because I have to refill my upper reservoirs much more often, now that my plants are mature and that the sun is stronger.
Oh ! And I have the pleasure to inform you that I’m on my way to taste my first cucumber in a few days.
Again, very warm thanks to you. I now have clues to go on with my experimentations. And I will give my worms eggshells again, eventually – as soon as I can regulate the pH.
If you have other comments or informations, you’re very welcome !

Worm Castings usually stay around a pH of 8 or more. The eggshells help regulate their environment around what they like which is around a pH of 8. I believe you would have to alter your tea after the fact. I think Earth Juice makes a natural pH up and down. Hope my limited knowledge helps.

You also might benefit from using “Prill” water to start with. Without going into a lot of details, Google up Prill water and check it out. You can buy the Prill beads at a lot of different sites on the net and Your plants will love it.
Luck to Ya !

Ok I also want to toss in my two cents on this issue and give a hand if possible. Gardening is not necessarily easy. I’m planning a garden for the spring and have been studying hard on the subject, through that study I find great people blogging about it and detailing their failures and sucesses and it has helped me and countless others. Don’t give up on this, keep plugging away at it and reading up and I’m sure you will at one point with experimentation come upon the particular solution that you need. I seriously hope for your personal sucess with this.

So here’s my two cents worth of knowledge on this subject and it is that… I keep fish and my knowlege is extensive when it comes to water quality, though that knowledge is not in need of use presently and I’m slightly rusty on the subject). the Total Hardness of your water is comprised of two components the General hardness and the carbonate hardness. See this short article http://www.thetropicaltank.co.uk/hardness.htm
The Carbonate hardness or Kh is what you need to deal with…simply put this is the buffering capacity of the water. If this value is too low your fishtank water (or hydroponic water) can swing wildly in the Ph values and not just up it can also drop dramatically and well be all over the charts sometimes depending on whats going on in your tank or hydroponics system (though my guess would be that your hydro system wont swing as much as my fishtanks could. When I was at my last home where there was town sewer and water the buffering capacity was nearly zero. My Ph would drop dramatically over time, my fish would become stressed physically, then disease would set in. It was a constant cycle of treating for disease (which generally also lowered the Ph) trying to save my rare and beautiful fish and lots of tears when I lost for instance a rare and precious moray eel that I had been keeping.

So what did I do. I went to a great site which actually was wetwebmedia.org (i think it was a .org) I learned and then I went to a salt water aquarium store (specifically salt water and I recommend you find one in your area) as salt water fish keeping is far more demanding and stringent. If you can find a marine aquarium store and tell them that your water is going to the alkaline end of the scale and ask them to set you up with a buffer for that particularly and something (I think) to increase your general hardness factor, I think you will conquer your problem. You will need a hardness test kit that tests both the Gh and the Kh. I wish I could be of more help to you but frankly when I moved to my new home it had its own Artesian well system and the water ended up being perfect from our tap and so my lab was gratefully folded up and put away and my fish are happy and healthy without all those formerly necessary solutions to even out the water. Overall though this is definitely your issue and it is correctable and the chemicals shouldn’t harm your plants or your health because ultimately they are the proper minerals to balance your water.

If we had issues with water that was too acidic we used to put a lump of coral in the bottom of the fish tanks. When the water became too acidic it would gently leach the calcium carbonate out of the coral until 7.0 Ph was reached. There was also something we used for too high an alkalinity but I can’t remember what it was. Ultimately your egg shells function in exactly the same way and shouldn’t harm your system, but they aren’t going to dissolve either unless your water is too acidic and calls for that calcium carbonate. There were indeed times that the dead lump of coral dissolved quite a lot faster than at other times. You may in fact find that your eggshells aren’t breaking down at all since your system is high in alkalinity, but really they shouldn’t cause harm.

I highly recommend that you take some time to read up on this subject at the link I gave you. Visit a marine aquarium shop that specializes in that or find a site for one that will allow you to ask a few Q’s and they can direct you better than I. Don’t go to Petco, they simply dont have the knowledge generally, though you may get lucky and find that one employee is a serious reef keeper or something (it does happen). They do sell the products you need though and likely at a better price.
A simpler easier fix…find a friend who has well water and test it. If you find that its a good dead 7.0 on the Ph scale, you could ask them for the water to make your wormpost tea with and perhaps reward them with a salad . That really may be enough to fix all of your issues. You would need to send them home with gallon jugs of water perhaps from time to time when you need to remake your solution. Rain water shouldn’t have the proper buffering capacity so I would skip trying that. Reasonably it should be the water running through the ground over various rocks and minerals that creates that buffering capacity that you are looking for.

Another thing that people often don’t think of is that this hobby of hydroponics and the hobby of fish keeping can go hand in hand as chums. Waste fish tank water is high in Nitrogen, and could be quite beneficial in your system. One would have to be cognizant of the other necessary needs of the plants though as potassium and phosphorus are likely to be low. But I would certainly think that adding some waste water from your fishtank (the stuff you vaccuum from the bottom of the tank) would be a boost for your plants in small doses. Never forget it all works together like two hands clasped together with fingers interwoven thus all the systems of the earth work in conjunction meshing together and affecting one another.

I wish you the very best of luck in this venture. Contact me if you care to. I am interested to know how it all turns out for you. Ultimately buffer that water and your swings will at least be not so wild and they may go away all together!

Thank you so much, PHE,
your post sounds logical and connects with the previous comments that I received. I will surely investigate, though it may take some time, since I’m very busy right now in other areas of my life. But you all give me a boost to keep on an find a solution.
If I could do that, it would be marvelous to produce my own nutrients at home !
I’ll keep you posted, surely, but be patient, as it may take a few months before I can go back to my experimentations.
Thanks again and Merry Christmas to everybody !

Do some research on plants that are “friendly” with one another. Friendly meaning that they balance each other’s nutrient needs. The nutrients that the plants leave behind from general solutions will change the conductivity(that’s what pH measures) of the water. If I come across an article or book that has a good set of planting instructions concerning plants that are friendly to one another, I’ll let you know.
Lettuce is super easy to grow, and it’s very resilient, which is why it’s the one that did the best, despite the misbalance in your system.

Hi, Stephen,
Usually, in a Window Farm, the advise is to group plants with similar needs so they can be fed by the same nutrient source, the main consideration being to give different nutrients to flowering plants than to leafing plants.
If I understand well your point, you suggest that besides this, plants retaining different nutrients would then affect the pH differently, one given plant compensating another’s effect on the general pH. Very interesting !

Please excuse me if I missed it. But when you say “worm compost tea” do you mean the run off from the bottom of your worm farm or, tea brewed from vermicast?
I ask only because I took to pouring the run off from my worm farm onto my plants. And it had a devastating effect on some of them.
I have since learned that the run off from the bottom of the worm farm is NOT GOOD for plants directly as it can be quite high in pathogens.
It is perhaps better to add it back into your worm farm or add it to the soil.
Look forward to hearing from you.
Cheers!

Hello ciaran !
You’re the second source mentionning this problem to my knowledge. In the beginning, I used the run off, but after a while, I switched to worm tea brewed from vermicast. Since you’re talking about pathogens, maybe harm was alreday done, though.
As I understand it, soil can handle a lot of variations or problems, while a hydroponic system will be very fragile to changes and stress. So, what you say makes sense.
I also learned something more, recently : the kind of worms used in vermicompost and as bait for fishing are not native and they are reported to make damages in forests where they accidentaly found their way in some parts of United States.
I read that their metabolism is faster than our native worms’ are and they are reported to process the layer of mulch too fast in the forests.
Here, in Canada, our winters are too cold for the red wrigglers that I use, though. It kills them.
Anyway, when I try again to feed my plants with worm tea, I’ll post an update.
Thanks !

Hey. I’m new here but I do know this: water likes to be at a pH of 7 and is a very good pH buffer in it of itself because the H+ and HO- ions deteriorate, escape, and become balanced again. This is likely your problem. May I suggest an air-tight reservoir? Otherwise if you could fins a plant that suck out the alkalinity (high pH) of the water, that should be placed on top so you can use straight nutrient water. Good luck on your project!

Thanks a lot phhealix, this makes sense also. I’ll have to reflect on this one. I didn’t use my Windowfarm this past winter, mainly because I was too busy on another project and because I want to turn it to electricity, for comparison purposes. But I want to restart it next fall.